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The Basin and Range Province in the western United States is an extensive region of alternating valleys and ridges caused by horst and graben as well as tilted block faulting. [ 1 ] The Condroz and Ardennes regions of Wallonia are good examples of a succession of horst and graben.
Opposing normal faults link at depth producing a horst and graben geometry, where horst refers to the upthrown fault block and graben to the down dropped fault block. The average crustal thickness of the Basin and Range Province is approximately 30–35 km and is comparable to extended continental crust around the world. [ 4 ]
Fault scarps are exposed on the horst block and expose the footwall of the normal fault. This is a type of block faulting known as grabens and horsts. This basin and range topography is symmetrical having equal slopes on both sides of the valleys and mountain ranges. Timelapse of tilted block faulting
In Nevada's recent geologic past, tectonic changes have created normal faults and creating the basin and range horst and graben terrain. Thinning of the upper crust caused deeper, highly metamorphosed rock masses to rise to the surface, where it is overlain by younger faulted and domed rocks.
As a result, steep normal faults formed the horst and graben landscape of the Basin and Range Province. Basalt intruded into the basins and evaporites and other sediments accumulated, including salt beneath Phoenix, clay and zeolites in the Bowie area and gypsum in both the San Pedro and Verde valleys.
Basin and Range Province of southwestern North America is an example of multiple horst/graben structures, including Death Valley, with Salt Lake Valley being the easternmost and Owens Valley being the westernmost. Lake George Basin, New York, U.S. Lake Tahoe Basin, California and Nevada, U.S. Republic Graben, Republic, Washington, U.S.
Geologists call this region the Basin and Range Province. Extensional forces causes rock at depth to stretch like silly putty and rock closer to the surface to break along normal faults into downfallen basins called grabens; small mountain ranges known as horsts run parallel to each other on either side of the graben. Normally the number of ...
The range is a classic example of horst and graben (fault-block) topography with pluvial (ephemeral) lakes occupying the graben basins. The eastern escarpment of the range overlooks the Surprise Valley in California and Warner Valley in Oregon, enclosed basins that contain Upper Alkali Lake , Middle Alkali Lake , and Lower Alkali Lake along the ...